Field of the Invention
The present invention relates to a spark plug, and in particular, relates to a spark plug that enables enhancement in dielectric strength performance.
Description of Related Art
A spark plug used for an internal combustion engine has an insulator made from an alumina-based sintered body mainly composed of alumina, for example. In general, the alumina-based sintered body is formed by sintering mixed powder containing a sintering additive including an Si component, etc. (for example, Patent Document 1). In the technology disclosed in Patent Document 1, the grain size in a crystal phase is controlled, whereby dielectric strength performance under high-temperature environment is improved.